Question

Date
Page
per
plastering its wall and deiling at the rate of Rs 2.50
square metre
Aroom is 9 m long ,6 m wide & 4 m high. Find the cost of​

Answer 1

AnswThe equal sides of an isosceles triangle are 20 cm and its area = 192 sq cm.

Let the base angles be m.

The area of the triangle = [2*20 cos m * 20 sin m]/2 = 192, or

400 sin m cos m = 192, or

200 [2 sin m cos m] = 192, or

2 sin m cos m = 192/200 = 0.96, or

sin 2m = 0.96, or

2m = arc sin 0.96 = 73.73979529, or

m = 73.73979529/2 = 36.86989765 deg.

The base of the triangle = 2 * 20 cos 36.86989765 = 32 cm.

Hence the perimeter of the isosceles triangle = 20*2+32 = 72 cm.

Check: 2s = 72, or s = 36.

Area of isosceles triangle = [36{36–32)(36–20)(36–20]^0.5

= [36*4*16*16]^0.5 = 6*2*16 = 192 sq cm. Correct.

Step-by-step explanation: